Efficient time-domain algorithm for calculation of harmonic currents produced by a cluster of ac/dc converters with the consideration of load variations

A useful time-domain algorithm to characterise harmonic currents produced by a cluster of three-phase AC/DC converters operated under either balanced or imbalanced supply voltages and asymmetrical source impedances with the consideration of load variations is proposed. The proposed method is based on the Poincareacute map concept for increasing the solution speed. An actual industrial rolling mill system with several DC motor drives operating in parallel is under test to show the usefulness of the proposed method. Simulations results are compared with those obtained by actual measurements. It shows that the harmonic currents determined by the proposed method agree well with those obtained by actual measurements. The proposed algorithm is relatively accurate, computationally efficient and robust.